In recent years, wind power stations that are each constituted by a plurality of wind turbine generators and send electrical power to the utility grid, so-called wind farms, are becoming widespread.
A wind power station needs to send electrical power to the utility grid such that the utility grid does not become unstable, and needs to reduce the electrical power supplied from the wind power station to the utility grid when the supply of electrical power from the wind power station to the utility grid becomes excessive.
PTL 1 discloses a system for preferentially reducing the output power of a wind turbine generator whose output power is the highest when the total output power of a plurality of wind turbine generators exceeds a predetermined amount.
Furthermore, PTLs 2 and 3 disclose wind-turbine-generator control methods in which, when the supply of electrical power becomes excessive, the rotational speed of the rotor having blades is increased to store rotational energy (inertial energy).